Fix the erroneous mergeinfo.
Fix the erroneous mergeinfo.

* www/merge-tracking/design.html
  (Merging changes into parents and then merging changes into children):
   Fix the erroneous merge source in the examples.

Patch by: ruz <ruz@bestpractical.com>

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion